import { DataExtractionResult, VisualizationData } from "../../DataExtractionResult";
import { LoadDataExtractorsFn } from "./LoadDataExtractorsFn";

export interface DataExtractorApi {
	/**
	 * Registers a single extractor.
	 */
	registerExtractor(extractor: DataExtractor): void;

	/**
	 * Registers multiple extractors.
	 */
	registerExtractors(extractors: DataExtractor[]): void;

	/**
	 * Extracts data from the result of `valueFn`.
	 * @valueFn a function returning the value to extract the data from.
	 * Is a function so that it's evaluation can depend on `evalFn`.
	 */
	getData(
		valueFn: () => unknown,
		evalFn: <T>(expression: string) => T,
		preferredDataExtractorId: string | undefined,
		variablesInScope: Record<string, unknown>,
		callFramesSnapshot: CallFramesSnapshot | null
	): JSONString<DataResult>;

	/**
	 * Registers all default (built-in) extractors.
	 * @preferExisting if `true`, existing extractors with the same id are not overwritten.
	 */
	registerDefaultExtractors(preferExisting?: boolean): void;

	setDataExtractorFn(id: string, fn: LoadDataExtractorsFn | undefined): void;
}

export type DataResult =
	| {
			kind: "Data";
			extractionResult: DataExtractionResult;
	  }
	| { kind: "NoExtractors" }
	| { kind: "Error"; message: string }
	| {
			kind: "OutdatedCallFrameSnapshot";
			callFramesRequest: CallFramesRequest;
	  };

export interface JSONString<T> extends String {
	__brand: { json: T };
}

export interface CallFramesRequest {
	requestId: string;
	requestedCallFrames: CallFrameRequest[];
}

export interface CallFrameRequest {
	methodName: string;
	pathRegExp: string | undefined;
}

export interface CallFramesSnapshot {
	requestId: string;
	frames: (CallFrameInfo | SkippedCallFrames)[];
}

export interface SkippedCallFrames {
	skippedFrames: number;
}

export interface CallFrameInfo {
	methodName: string;
	source: { name: string; path: string };
	vars: Record<string, any>;
}

export interface DataExtractor {
	/**
	 * Must be unique among all data extractors.
	 */
	id: string;

	/**
	 * Filters the data to be extracted.
	 */
	dataCtor?: string;
	getExtractions(data: unknown, extractionCollector: ExtractionCollector, context: DataExtractorContext): void;
}

export interface ExtractionCollector {
	/**
	 * Suggests a possible extraction.
	 */
	addExtraction(extraction: DataExtraction): void;
}

export interface DataExtractorContext {
	/**
	 * Evaluates an expression in the context of the active stack frame.
	 */
	evalFn: <TEval>(expression: string) => TEval;

	readonly expression: string | undefined;

	readonly variablesInScope: Record<string, () => unknown>;

	extract(value: unknown): VisualizationData | undefined;

	readonly callFrameInfos: readonly (CallFrameInfo | SkippedCallFrames)[];

	addCallFrameRequest(request: CallFrameRequest): void;
}

export interface DataExtraction {
	/**
	 * Higher priorities are preferred.
	 */
	priority: number;

	/**
	 * A unique id identifying this extraction among all extractions.
	 * Required to express extraction preferences.
	 */
	id?: string;

	/**
	 * A user friendly name of this extraction.
	 */
	name?: string;

	extractData(): VisualizationData;
}
